Protecting device for the cooling cylinders of the electrodes of furnaces heated by arcs



May 19, 1925. 1,538,286

E. KRAUSE PROTECTING DEVICE FOR THE COOLING CYLINDERS OF THE ELECTRODES0F FURNACES HEATED BY ARCS Filed April 17, 1924 mii I f /r of fine/war;6-Ml 131 Y Patented May 19, 1925.

UNITED STATES PATENT. OFFICE.

EDMUND KRAUSE, OF HENNIGSDORF, NEAR- BERLIN, GERMANY.

PROTECTING DEVICE FOR- THE COOLING CYLINDERS THE ELECTRODES OF FUR-NACES HEATED BY- ARCS.

Application filed April 17, 1924. Serial No. 707,252.

T 0 all whomit may concern:

Be it known that I, EDMUND KRAUsE, a citizen of the German Republic,residing at Hennigsdorf, (Osthavelland), near Berlin, Germany, haveinvented a certain new and useful Protecting Device for the CoolingCylinders of the Electrodes of Furnaces Heated by Arcs, of which thefollowing is a s ecification.

n electric furnaces heated by arcs, either the electrodes electricallyinsulated, 'are passed through the cooling cylinders or rings in whichcase the cooling rings are connected to the furnace body by a metallicand electrically conducting connection, or the electrodes are passedthrough the cooling cylinders or rings without insulation, in which casethe cooling rings are electrically insulated from the body of thefurnace.

In both cases there is frequently notice able the disadvantage that whenan-electrode breaks the are which is produced at the point of fractureperforates the cooling ring or cylinder surrounding the electrode sothat the cooling water flows into the furnace thus causing interruptionin the operation of the furnace for long periods, and involvingexpensive repairs.

To meet this disadvantage there is provided, according to the invention,a protecting device the purpose of which is to insulate electrically theelectrodes from the cooling cylinders or rin s and also the coolingcylinders or rings from the furnacebody. By such double insulation it ispossible for the cooling cylinders or rings to be connected so. thatthere is an electrically conducting path, to the furnace transformer orthe cur rent generator by the switching-in of relays or maximumcurrentcut-outs, with or without the interposition of resistances.

By means of this protecting device, the slightest contact of the arcwith the cooling cylinder immediately opens the main switch of thefurnace transformer or current generator, and it is prevented from beingclosed during such time as the broken electrode is being replaced by anew one.

The device according to the invention is diagrammatically illustrated,by way of example, in the accompanying drawing.

The electrode a, which is connected to phase I of the transformer b, isinsulated electrically both from the cooling cylinder 0 and from thefurnace cover (I by means of the insulating material 6. The coolingcylinder 0 is connected by an electrical conductor f, through the seriesresistance 9 and a relay or maximum current cut-out h, to the zero pointi of the transformer. Instead of the conductor f being connected to thezero point 2' of the transformer b, it may be connected upto one orother of phases II and III, in which case the conductor is completedthrough the transformer.

, If the electrode a becomes broken, the are produced contacts with thecooling cylinder 0' thus producing a closed circuit from the electrode athrough the cooling cylinder 0, the resistance 9 and the relay h, to thefurnace transformer b or current generator. By this means the relay isactuated and instantly closes the cut-out current I: of the main switchZ and simultaneously locks the switching-in current to the long distanceconnection of the main switch Z. The relay h is provided with amechanical locking device m, which looks the relay after its operationuntil the mechanical lock is released by hand. By the use of thismechanical locking mechanism and by numbering the relays to correspondto the electrodes it is at once pos-. sible to determine where thebroken electrode is situated.

Instead of actuating the protecting device by the furnace transformer, aspecial or secondary source of current. may be provided which suppliesthe current for actuating the switching-out relay upon an electrodebeing broken.

I claim: p

1. A protecting device for the cooling cylinder of the electrodes offurnaces heated by arcs, characterized in that not only are theelectrodes insulated from the cooling cylinders or rings, but thecooling cylinders or rings are themselves insulated from the bodyof thefurnace and are connected by an electrically conducting path to thefurnace transformer or current generator, a switch device, which becomeseffective in case of an electrode breaking, being interposed.

2. A protecting device according to claim 1, characterized in that arelay or maximum current cut-out is provided in the electricallyconducting path between the cooling cylinders or rings and the furnacetransformer, with or without the interposition of resistances, whichcuts out the furnace when an ductor with relay,

electrode breaks and thereby prevent the cooling cylinders or rings frombeing fused. 3. A protecting device according to claim 1, cha acterizedin that the relay or maximum current cut-out connected up into theprotecting conductor is provided with a locking or stop device by whichthe oven is prevented from being rendered operative when an electrodehas broken.

4. A protecting device according to claim 1, characterized in that foreach electrode there is provided a separate protecting conlockingdevices or stops and the like, whereby, by means of an indicatingdevice, an indication is given that an electrode is broken andconsequently an arc EDMUND KRAUSE.

